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Recent Results on New Phenomena from CDFPASCOS ’04

This paper presents the recent results on the search for new phenomena, including SM and BSM Higgs searches, supersymmetry searches, di-lepton and di-photon searches, and other searches. The major challenges faced by experimentalists are also discussed.

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Recent Results on New Phenomena from CDFPASCOS ’04

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  1. Recent Results on New Phenomena from CDFPASCOS ’04, August 16-22Boston, MA Dmitri Tsybychev on behalf of CDF Collaboration U. Florida/SUNY at Stony Brook ?

  2. Outline • Introduction • SM and BSM Higgs searches • Supersymmetry searches • Di-Lepton and Di-Photon searches • Other searches • Summary

  3. Major Challenges • Predicted new physics cross-sections are within the reach of the Tevatron • Cross-sections are strongly dependent on particle masses, less so on model parameters • Backgrounds can be orders of magnitude larger than the signal • Challenge for the experimentalists : HOW ! • Production rates, luminosity,… • Trigger (keep 1 out of 24000 collisions) • Detection efficiency • Suppress background • Differentiate signal and background Higgs LQ LED Use combination of data/simulation to devise cuts, predict backgrounds/estimate acceptances

  4. Use both signature/model based searches Sensitivity to many models Best sensitivity for given model Unbiased Investigate all possible signatures Report results on searches with Run II data (L~200 pb-1) Coming soon first results in 500 pb-1 dataset Models Higgs MSSM Extra Dimensions Leptoquarks Compositeness W’, Z’ … Searches for New Phenomena Experimental signatures • g • e, m (generically lepton) • t • Jets (quarks and gluons) • Heavy Flavor tagging (b,c) • Missing transverse energy

  5. For mh > 135 GeV/c2 hWW dominates Can look for ggh WW,ZZ Low SM background Many additional Higgs bosons in models beyond SM, some of them have higher sensitivity Higgs boson is crucial to our understanding of EWSB For mh < 135 GeV/c2 hbb dominates ggh suffers from large SM background SM Higgs

  6. For Mh > 135 GeV/c2 hWW*ll (e) Require 2 isolated opposite sign leptons (pT>20 GeV/c) Missing ET > 25 GeV No jets Z removal Dilepton ivariant Mass Mll< ½Mh Mh 160 170 180 WW 4.5 ± 0.5 5.4 ± 0.6 6.5 ± 0.8 Other 1.3 ± 0.4 1.9 ± 0.5 2.4 ± 0.7 Data 3 7 8 Expected signal ~ 0.2 Extract 95% CL limit using likelihood fit To angular distribution SM Higgs

  7. Golden mode hWbbl (e) Require exactly 1 lepton (pT>20 GeV/c) Missing ET>20 GeV Excatly 2 jets ( 1 or more SVX b-tag) Need highly efficient, pure b-tagging b~ 53% (in t-tbar events) c ~ 3% uds,g < 1% Need excellent di-jet resolution currently 17 %  10 % achievable Expect 60.5 ± 4.4 background events 25.2 ± 3.2 W +hf Observe 62 Signal 0.7 for Mh =115 GeV/c2 Use di-jet mass spectrum to exctract 95 % CL SM Higgs

  8. Still order of magnitude higher than SM prediction Combine with other channels hZbb Need more data Interesting for other EWSB mechanisms Technicolor Results depend on m(ρT) and m(T) SM Higgs

  9. SUSY new type of symmetry Fermions  Bosons Many models In MSSM 5 Higgs particles CP-even: h,H CP-odd: A Charged: H± tan - ratio of VEV of scalar fields For neutral Higgs couplings to third generation can be enhanced at high tan Abb is tough - consider A Narrow jet of track/energy for hadronic -id Isolated from nearby tracks/energy Add reconstructed 0 MSSM Higgs

  10. Select events with one l (e) and one hadronic  deacy HT > 50 GeV (scalar sum of  momenta and missing ET) Missing ET should not point in opposite direction to  decay products Mass resolution worse at higher masses Use binned likelihood fit to mass spectrum set 95% CL limit Limit is order of magnitude higher than prediction (tan) MSSM Higgs

  11. H±± predicted in models that contain Higgs triplets Left-Right (LR) symmetric models SUSY LR models : low mass (~100 GeV – 1 TeV) Partial decay width: hll – Yukawa coupling, free parameter, determines H±± stable or prompt Search for H±±

  12. Search for H±± • Stable H±±: • Two heavily ionized tracks in tracking chamber • Muon-like in muon chambers • MIP-like in calorimeter • Require a “muon” with pT>20 GeV/c and another track with pT>20 GeV/c • 0 events observed • Prompt H±±: • Two same sign leptons (ee,e,) • Very small SM background • Search for a lepton pair in mass window of 10%*M(H++) (~3s detector resolution) • 0 events observed

  13. 3rd generation squarks could be light Large top mass  light stop At large tan  light sbottom If gluino is light enough the pair production at Tevatron is large Assume R-parity conservation LSP – stable Good candidate for dark matter Branching ratio strongly depends on sparticle masses Assume Assume m(gluino) > m(b1) > m(Χ10), m(t) + m(Χ1+ ) > m(b1) BR (b1 bΧ10) = 100% Sbottom from Gluino Decay 4 b-jets + Missing ET

  14. Event selection: Missing ET > 80 GeV 3 jets ( 1 or 2 SVX b-tags) Missing ET direction is not collinear with jets No isolated leptons No excess observed in data Large exclusion in sbottom-gluino plane Sbottom from Gluino Decay

  15. Looked at di-lepton invariant mass and angular distributions to search for new phenomena Select events with 2 high pT leptons Many model predict enhancement at higher mass Extra Dimensions, Z’, Technicolor … Expect mass peaks, enhancement in the spectra Data in good agreement with SM predictions Extract limits on many new models from the spectra Searches in Di-Leptons ee 

  16. Search for Z’ in  channel • Look in high mass region for new physics • M (Missing-ET,,) > 120 GeV • Missing-ET > 15 GeV • |Δφ(Missing-ET, )| > 30º • Expect 2.83±0.39 events, see 4 Exclude Z´<394 GeV/c2 95% CL (Z´ with SM couplings)

  17. The large gap between EW and Planck scales is assumed to be due to the extra dimensions Models predict different geometry, number of extra dimensions Only Graviton propagates in the ED, SM particles are trapped in 3-D brane The gap is narrowed by reducing the effective fundamental scale to ~ 1 TeV In the compactified ED, gravity expands into a series of Kaluza-Klein (KK) states For example: Randall-Sundrum ED Model 1 highly curved extra dimension Gravity localized in the ED Scale of physical phenomena on the TeV-brane is specified by the exponential warp factor = MPle-kRc New parameters: First graviton excitation mass: m1 Ratio: k/MPl g q Gkk Gkk _ g 400 600 800 1000 q q,e,,, q,e,,, Extra Dimensions d/dM (pb/GeV) 10-2 10-4 10-6 10-8 K/MPl 1 0.7 0.5 0.3 0.2 0.1 Tevatron 700 GeV KK graviton

  18. Search for high mass γγ events in 345 pb-1 2 isolated  ET>15 GeV In addition to ee,  channels Can combine , ee,  channels to set a more stringent limit qq channel in progress Di-Photon

  19. Leptoquarks at the Tevatron • Remarkable symmetry between quarks and leptons in SM  new symmetry • Leptoquarks are predicted in GUT models, SUSY (with RPV), Technicolor and Compositeness • Connect leptons and quarks in the SM • Leptoquarks are color triplet bosons (scalar or vector) with lepton number and fractional electric charge • Pair produced at the Tevatron • Assumed to couple to leptons and quarks within the same generation • b – branching ratio to charged lepton • Decay: • Experimental signatures: • Missing ET + 2 jets • 1 isolated lepton + Missing ET + 2 jets • 2 isolated leptons + 2 jets

  20. 1st and 2nd Generation Leptoquarks • Generation  Mass Limit(GeV/C2) 1 1 >230 0.5 >176 (182 Run I) 0 >117 2 1 >241 0.5 in progress 0 >124 (Run I) LQ1LQ1 eejj LQ2LQ2 jj m(LQ) > 230 GeV/c2 95% CL

  21. Produced in pairs in Drell-Yan like processes Search for highly ionizing tracks in Time-of-Flight system and tracking chamber Dedicated monopole trigger based on TOF 0 events observed Magnetic Monopole

  22. Summary • Good sensitivity beyond existing limits for new physics at Tevatron • Have now 5x more data than in Run I • Many more analyses in progress • Stay tuned • Visit CDF physics result web page for new results http://www-cdf.fnal.gov/physics/physics.html • Can address key SM question before LHC • Much excitement at both Tevatron experiments for physics beyond SM • Will be more exciting if see some evidence for new physics

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